Screen E-Book (.PDF) - MacDermid Autotype

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MoiréDescriptionAn unexpected pattern in the print which was not in the artwork. It is always associatedwith regularly repeating patterns in the print, either dots in 4-colur process or lines. In 4colour process it is generally not present over the whole print area but related to areas ofparticular density.CauseMoiré is caused by the interference of regularly repeating patterns. They can be dot to dot,dot to mesh or line to line or line to mesh.This is an example of classic 15° moiréTechnical referenceSee ‘Moiré causes and cures’ chapter.SolutionUse the MMC to find a mesh/LPI combination which will not cause moiré.Change the screen angles.Use the problematic angle for yellow to make the moiré less noticable.Change the mesh count slightly for the screen causing the moiré.SkippingDescriptionDotty pattern in the 4-colour UV ink print, usually in mid tones.124
Under magnification the dots have notprinted cleanly and look like ‘puppy paws’.CauseDots are not printed cleanly because themesh is being held away from the substratesurface by previously printed dots.Technical referenceSee ‘Problem solving in the real world’chapter.SolutionReduce the height of the printed dots byusing a low EOM stencil, 3μm profile isideal.SolutionIncrease time between printing and curingto allow flow.Change to a mesh with smaller diameter.Change the ink to one with better flowcharacteristics.Saw toothed lines or dotsDescriptionThe printed edge of the image is moreragged than the positive.Mesh marksDescriptionThe ink has a textured surface.CauseThe ink is not flowing out well after themesh and ink have separated.Technical referenceSee ‘Optional theory’ chapter.125
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HowHow to be agreat ScreenprinterEd
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About this eBookI’m passionate ab
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06Table ofContents07 The Theory Bit
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The wrong way: a strong-deep flood.
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why a light flood is recommended so
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This is the single most important f
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When I first pointed this out to my
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The Theory Bit20Why is the 1-2-3 so
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The mesh does the meteringThe 1-2-3
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This gives us the ‘real’ TIV fo
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simple, in-control process.Years of
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The Optional Theory28At the shear r
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I’ve come across examples in all
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The Optional TheoryOur 50µm line b
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oughness can slow slumping; it prob
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The Optional TheoryThe exact part o
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atches of the ‘same’ mesh. My f
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The Optional Theory40The industry r
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the screen frame itself to compensa
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Print Faults - Making and fixing th
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Print FaultsThey include tape marks
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Wrong ink - Too much viscous drag (
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DustPrint FaultsWe threw some dust
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What’s the best order to print yo
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Colour shifts54high-frequency (non-
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We formed our own (subjective) opin
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And the winner is...Colour shifts58
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Getting the right exposureAnna Harr
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Getting the right exposureThe light
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3/4 full exposureEFFECTS: Emulsion
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Getting the right exposureThere is
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Undercutting from a rough stencilSo
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Getting the right exposure(or numbe
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Solving problems in the real worldA
Page 74 and 75: Solving problemsThe simple act of r
Page 76 and 77: Emulsion coatingThe advice about cl
Page 78 and 79: Solving problemsA quick tip to help
Page 80 and 81: stencil causes a thick edge needed
Page 82 and 83: Solving problemsThis screen-shot fr
Page 84 and 85: A modest Rz gives amodest absolute
Page 86 and 87: Solving problemsThe root cause of n
Page 88 and 89: Now the ink fully fills the extra s
Page 90 and 91: Solving problems90Stencil X gives b
Page 92 and 93: Moiré, causes and curesSteven Abbo
Page 94 and 95: Moire, causes and cures94fluential
Page 96 and 97: Figure ii. The overlayedpattern fro
Page 98 and 99: Moire, causes and cures98Causes and
Page 100 and 101: 2 15° moiréIt’s an unfortunate
Page 102 and 103: Moire, causes and cureson top of an
Page 104 and 105: Ideal. Find a RIP with an option fo
Page 106 and 107: Moire, causes and curescan’t pick
Page 108 and 109: frequency tend to have a lower ampl
Page 110 and 111: Moire, causes and curesis a half-tr
Page 112 and 113: Incidentally, note that the ratio o
Page 114 and 115: Moire, causes and cures114So, surpr
Page 116 and 117: grid) in a conventional set that wa
Page 118 and 119: Moire, causes and cures118what this
Page 120 and 121: Arguably the skipping takes place p
Page 122 and 123: Moire, causes and curesSummaryAs Ma
Page 126 and 127: Problem solving GuideCause1. The mo
Page 128 and 129: Dark spots / HickiesDescriptionDark
Page 130 and 131: Problem solving GuideTechnical refe
Page 132 and 133: 6. Substrate unstable.7. Changes in
Page 134 and 135: Glossary of terms used in this eBoo
Page 136 and 137: Glossary136Moiré amplitudeThe ampl
Page 138: A Macdermid Autotype HowTo eBookEdi
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